Podcast
Questions and Answers
What is the first action to take upon entering the lab?
What is the first action to take upon entering the lab?
Which of the following is NOT a safety rule when working in the lab?
Which of the following is NOT a safety rule when working in the lab?
Where should contaminated throwaway items be disposed of?
Where should contaminated throwaway items be disposed of?
What is the purpose of aseptic techniques in the lab?
What is the purpose of aseptic techniques in the lab?
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In which situation would you use an inoculating needle?
In which situation would you use an inoculating needle?
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What is required to create a pure culture from a single cell?
What is required to create a pure culture from a single cell?
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How is a streak plate used in microbiology?
How is a streak plate used in microbiology?
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What action should be taken with your hands before exiting the lab?
What action should be taken with your hands before exiting the lab?
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What is the purpose of the fine focus when using a microscope?
What is the purpose of the fine focus when using a microscope?
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Which staining procedure uses crystal violet?
Which staining procedure uses crystal violet?
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What is the total magnification when using a high dry lens of 40x?
What is the total magnification when using a high dry lens of 40x?
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What differentiates gram-positive bacteria from gram-negative bacteria in the gram stain?
What differentiates gram-positive bacteria from gram-negative bacteria in the gram stain?
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What is the initial step involved in the gram staining procedure?
What is the initial step involved in the gram staining procedure?
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Which of the following best describes a negative stain?
Which of the following best describes a negative stain?
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Which step in the acid-fast staining procedure involves heat?
Which step in the acid-fast staining procedure involves heat?
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What type of stain would you use to visualize endospores?
What type of stain would you use to visualize endospores?
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Study Notes
General Lab and Safety Procedures
- Disinfect bench top with lab disinfectant upon entering the lab.
- Gather necessary materials, including lab manual and pencil, at the start.
- Wash hands with soap and water for 20 seconds when arriving and before leaving.
- Return all lab materials as directed by the instructor before exiting.
- Disinfect bench top and dry with paper towels after completing the lab.
- Push chairs under the bench to maintain a clean workspace.
- Adhere to safety rules: always wear gloves and goggles with chemicals.
- Tie hair back, do not eat or drink, maintain short nails, and wear enclosed shoes.
- Stay prepared and organized for each lab session.
Waste Disposal
- Contaminated items must be disposed of in biohazard containers.
- Non-contaminated materials can go in the regular trash bin.
- Contaminated glassware is to be placed in the sterilization area.
Aseptic Culturing Techniques
- Aseptic techniques prevent contamination of cultures and the environment by microorganisms.
- Agar is a solid growth medium made from seaweed.
- Broth is a liquid growth medium, typically used for bacterial culture.
- Inoculation transfers microbes between cultures.
- Inoculating loop and needle are essential tools used to streak bacteria or stab into solid media.
Inoculation Steps
- For broth to broth: Sterilize the loop, retrieve culture, flame the tube, and withdraw a bead of culture.
- For broth to agar slant: Same initial steps as broth to broth, with additional passing through and flaming the tube.
- For broth to agar deep: Sterilize needle, insert into tube, and withdraw after inoculation.
- Label and incubate media properly, particularly agar plates, using tape for clear identification.
Streak Plates and Pure Cultures
- Streak plates aim to isolate single bacterial cells on Petri dishes.
- Pure cultures consist of a single microbe type, achieved by isolating from a single cell.
Introduction to the Microscope
- Familiarize with all microscope parts and their functions.
- Calculate total magnification using the objective and ocular lens values.
- 4x → 40x, 10x → 100x, 40x → 400x, 100x → 1000x.
- Key functions include magnification, resolution (detail visibility), and parfocalism (maintenance of focus).
Focusing and Specimen Viewing
- Start with the lowest magnification (4x or 10x) for initial viewing.
- Position the slide on the stage, using coarse focus to bring the specimen into view.
- Center the specimen and adjust lighting before fine-tuning focus.
- Switch to higher magnification if necessary, re-adjusting focus.
Cleaning and Storing Microscopes
- Lower the stage and rotate to 4X objective before cleaning.
- Use lens cleaner and a Q-tip for lenses, and a Kimwipe for the stage and knobs.
- Turn off the light, unplug the microscope, and wrap it carefully.
- Ensure instructor checks the stored microscope.
Staining Labs
- Simple stain: Basic dyes enhance visibility of bacterial shape and arrangement.
- Negative stain: Stains the background, leaving cells clear for structural analysis.
- Capsule stain: Identifies bacteria with protective capsules.
- Gram stain: Differentiates bacteria based on cell wall characteristics (purple for Gram positive, pink for Gram negative).
- Acid-fast stain: Identifies bacteria with waxy cell walls, visualized in red.
Contrast Between Stains
- Basic stains directly color the cells.
- Acidic stains color the background instead, leaving cells unstained.
Differential Staining Procedures
- Gram stain steps: Crystal violet, iodine, ethanol, and safranin.
- Negative stain uses nigrosine for visualization.
- Acid-fast stain steps: Carbon fuchsin, heat, iodine, acid-alcohol wash, and methylene blue.
- Endospore stain procedures: Malachite green, heat, rinse, and safranin.
- Basic stain: Crystal violet followed by water rinse.
- Capsule stain: Crystal violet and copper sulfate for visualization of encapsulated bacteria.
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Description
Test your knowledge of lab safety and general lab procedures with this quiz. Review the important steps you should take when entering and exiting the laboratory. Ensure you're familiar with performing essential tasks to maintain a safe working environment.
